Orthodontic bracket

ABSTRACT

An orthodontic bracket placed on a side surface of a tooth for correcting irregularities of teeth is disclosed, which enables orthodontic treatments to be performed without reset of a bracket body and an arch wire with respect to the tooth even in an advanced stage of the treatments. The orthodontic bracket comprises a bonding plate having a bonding surface matching a curve of the tooth, a base having a bottom surface united with the bonding plate and an upper surface as a sliding surface parallel to a long axis of the tooth and taking an approximately rectangular shape in plan with a convex curve formed in accordance with the long axis of the tooth, and a bracket body set on the sliding surface of the base so as to be slidable along the tooth axis. The base has, at the opposite upper sections of the sliding surface, confronting groove-like parallel rails adapted to let slidably the opposite portions of the bracket body therein. Each rail has, at its opposite ends, stoppers to prevent detachment of the bracket body. The sliding surface has, at its widthwise center, a longitudinally-extending visible median line. The bracket body has, on its upper surface, wire slots arranged approximately orthogonal to the above tooth axis.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an orthodontic bracket useful in correcting irregularities of teeth.

2. Description of the Related Arts

To subject orthodontic treatment to patients troubled with irregularities of teeth, more than one orthodontic bracket made of a material including metals and resins etc. is usually used. Each orthodontic bracket has a bracket body having, on its upper surface, wire slots adapted to hold an arch wire across the upper surface of the bracket body. Each orthodontic bracket is bonded with an adhesive to a side surface (or a front surface in the case of an incisor target, or a side surface in the case of a molar target) of each tooth subjected to orthodontic treatment.

For bonding each orthodontic bracket to each corresponding tooth side surface, a bracket position is set with respect to each tooth such that the bracket body and the tooth specified as a bonding target (or a bracket body's center line parallel to a vertical direction of the tooth as the bonding target and a tooth center line) are in alignment with each other and that an axis of the arch wire held with the wire slots of each orthodontic bracket is arranged linearly in parallel to a linear occlusal plane of teeth supposed to be obtained after orthodontic treatment. Then, bonding of each orthodontic bracket to the set bracket position given to each tooth is performed.

With the arch wire held with the wire slots of each orthodontic bracket placed on each corresponding tooth side surface as described the above, the orthodontic brackets are connected together through the arch wire. Then, insertion of the opposite ends of the arch wire into respective buccal tubes united with more distal adequate teeth is performed with the arch wire tensed, followed by connection of the arch wire to the respective buccal tubes.

With each orthodontic bracket placed on each corresponding tooth side surface as described the above, the orthodontic treatment is carried out in such a way as to apply elastic recovery force of the arch wire to provide distal movements (or movements from an incisor side toward molars) or mesial movements (or movements from a molar side toward incisors) of each tooth requiring the orthodontic treatment, or alternatively, to perform adjustment of occlusion between upper and lower teeth and elimination of torsion.

There are cases where the orthodontic treatment is given after extraction of tooth such as crowding or without extraction. However, as is obvious from the above description, in either case, setting of the bracket position is of quite importance in order to bond each orthodontic bracket in proper position with respect to each tooth as the bonding target.

Some of important problems involved in bonding of each orthodontic bracket in its accurate posture to the above bracket position of the corresponding tooth are how to select position and/or direction of the bracket body for parallel arrangement between the axis of each wire slot in the bracket body and the linear occlusal plane of teeth, how to select the position and/or direction of the bracket body for alignment between the bracket body and the corresponding tooth, and how to match a gradient of the bracket body to the corresponding tooth side surface.

To solve the above problems, there is provided Japanese Patent Laid-open No. 8-112293, for instance, which discloses an orthodontic bracket having a bracket body having, at its opposite sides, a pair of tie wings each having, in the center, a wire slot formed across the corresponding tie wing, wherein each tie wing has, on its median line, a first visible reference line parallel to a long axis of the tooth, and each wire slot has, on its axis intersecting the first visible reference line, a second visible reference line parallel to a linear occlusal plane of teeth. The orthodontic bracket of this type ensures that bonding of this orthodontic bracket to the corresponding tooth side surface with the adhesive may be performed using the first and the second visible reference lines, permitting the bracket to be bonded in its proper position in accordance with the long axis of each corresponding tooth and with the linear occlusal plane of teeth.

To solve the above problems, there is also provided Japanese Patent Laid-open No. 2005-192989, for instance, which discloses an orthodontic bracket having a mark on a contour line having a center line located on a bottom surface of each wire slot of a bracket body so as to extend in a longitudinal direction of each wire slot and defined by intersection of a plane vertical to the bottom surface of each wire slot and the surface of the bracket body. The orthodontic bracket of this type ensures that alignment of the mark with a mid-transverse plane of the tooth supposed to be bonded to the bracket allows a bracket base point to be located on the mid-transverse plane, permitting the bracket to be located accurately on the tooth as the bonding target.

However, the orthodontic bracket, even after placement of this bracket in its accurate posture in the bracket position of each tooth is achieved, brings about distal or mesial movements of the tooth requiring the orthodontic treatment, with advance of the orthodontic treatment depending on clamping force of the arch wire, resulting in a change in occlusion between the upper and lower teeth. Thus, the orthodontic brackets of the above types in a conventional technology give rise to such problems that the change in occlusion of teeth with the advance of the orthodontic treatment necessitates a change of bracket position setting, causing frequent reset of the bracket body and the arch wire with respect to each corresponding tooth. Further, frequent reset of the bracket body and the arch wire requires much time for the orthodontic treatment, and besides, forces heavy burden upon the patients.

SUMMARY OF THE INVENTION

The present invention has been undertaken to eliminate troublesome reset of a bracket body and an arch wire with respect to each corresponding tooth unlike the conventional technology, and its object is to provide an orthodontic bracket that enables orthodontic treatment to be performed without requiring reset of the bracket body and the arch wire even in an advanced stage of the orthodontic treatment.

To attain the above object, an orthodontic bracket according to the present invention comprises a bonding plate having a bonding surface matching a curve of a tooth; a base having a bottom surface united with the bonding plate and an upper surface as a sliding surface parallel to a long axis of the tooth, and taking an approximately rectangular shape in plan with a convex curve formed in accordance with the long axis of the tooth; and a bracket body set on the sliding surface of the base in such a way that the bracket body may slide along the long axis of the tooth, wherein the base has, on the opposite upper sections of the sliding surface, confronting groove-like parallel rails adapted to let the opposite portions of the bracket body therein slidably, each rail has, at its opposite ends, stoppers to prevent detachment of the bracket body, the sliding surface has, at its widthwise center, a longitudinally-extending visible median line, and the bracket body has, on its upper surface, wire slots arranged approximately orthogonal to the long axis of the tooth.

For preparations for the orthodontic treatment with the orthodontic bracket according to the present invention, the bracket body is set on the sliding surface of the base slidably by letting the opposite portions of the bracket body in the respective rails of the base.

The above preparations are followed by adhesive-bonding of each base through the bonding plate to the side surface of each tooth as the bonding target, with each base held such that its median line is in alignment with the long axis of each tooth as the bonding target, and with each bracket body held such that the axis of each wire slot is arranged in parallel to a properly linear occlusal plane of the teeth supposed to be obtained after orthodontic treatment (or a normally linear occlusal plane).

Then, with the arch wire held after being let in the wire slots of each bracket body, fastening of the bracket body to the base together with the arch wire is performed with a fixture such as a ligature wire to prevent the bracket body from sliding along the sliding surface of the corresponding base. At the same time, interconnection of the orthodontic brackets is performed.

Afterwards, insertion of the opposite ends of the arch wire into buccal tubes united with more distal teeth is performed, followed by connection of the arch wire to the buccal tubes to apply tension to the arch wire and also to press each bracket against each corresponding tooth. With this arrangement, the tooth requiring the orthodontic treatment gradually shifts toward its correct position such as to be given the orthodontic treatment.

When the orthodontic treatment of the tooth to be orthodontically treated is advanced to a stage necessitating the change in set position of the bracket with respect to the tooth to be orthodontically treated, repositioning of the bracket is performed by shifting the bracket body along the sliding surface of the base by a required distance in the vertical direction of the tooth to be orthodontically treated through a process of loosening or detaching the fixture such as the ligature wire, while loosening the arch wire. Then, with the repositioned bracket body re-fixed to the sliding surface of the base with the fixture such as the ligature wire without sliding, reinsertion of the opposite ends of the arch wire into the respective buccal tubes is performed, followed by reconnection of the arch wire to the respective buccal tubes to reapply the tension to the arch wire.

Thus, there is no need to reset the bracket body and/or the arch wire every time the orthodontic treatment of the tooth to be orthodontically treated is advanced to the stage necessitating the change in set position of the bracket with respect to the tooth to be orthodontically treated. Accordingly, the orthodontic bracket of the present invention enables the orthodontic treatment to be performed in a shorter period of time, and besides, may contribute to relieve the patient from one's burden by far.

Further, the orthodontic bracket of the present invention has the base of the convex-curved shape in accordance with the vertical direction of the tooth, permitting more successful matching of the convex-curved base to the tooth side surface to be obtained, and also permitting an installed posture of the bracket body set on the sliding surface of the base to match the tooth side surface more successfully.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects and features of the invention will become more apparent from the following description of preferred embodiments with reference to the accompanying drawings, in which:

FIG. 1 is a front view showing placement of an orthodontic bracket of a first embodiment according to the present invention to a side surface (or a front surface) of a tooth;

FIG. 2 is a plan view showing a base in the orthodontic bracket in FIG. 1;

FIG. 3 is a sectional view taken along an arrow A-A in FIG. 2:

FIG. 4 is a fragmentary enlarged sectional view taken along an arrow B-B in FIG. 2:

FIG. 5 is a plan view showing a bracket body in the orthodontic bracket in FIG. 1:

FIG. 6 is a sectional view taken along an arrow C-C in FIG. 6:

FIG. 7 is a sectional view taken along an arrow D-D in FIG. 5:

FIG. 8 is a plan view showing the orthodontic bracket of a second embodiment according to the present invention including a modification of the bracket body;

FIG. 9 is a sectional view taken along an arrow E-E in FIG. 8:

FIG. 10 is a sectional view taken along an arrow F-F in FIG. 8:

FIG. 11 is a fragmentary front view showing a state of intruding treatment of the tooth using the orthodontic bracket according to the first embodiment;

FIG. 12 is a fragmentary front view showing a completion of intrusion of the tooth from the state in FIG. 11;

FIG. 13 is a fragmentary front view showing a state of extruding treatment of the tooth using the orthodontic bracket according to the first embodiment;

FIG. 14 is a fragmentary front view showing a completion of extrusion of the tooth from the state in FIG. 13;

FIG. 15 is a schematic-front view showing the orthodontic bracket of a third embodiment according to the present invention;

FIG. 16 is a right side view of the orthodontic bracket in FIG. 15;

FIG. 17 is a schematic front view showing the orthodontic bracket of a fourth embodiment according to the present invention;

FIG. 18 is a sectional view taken along a line G-G in FIG. 17;

FIG. 19 is a sectional view taken along a line H-H in FIG. 17;

FIG. 20 is a fragmentary exploded perspective view showing a relation between the base and a fixture in the orthodontic bracket of a fifth embodiment according to the present invention;

FIG. 21 is a front view showing the orthodontic bracket of the fifth embodiment involving use of the base and the fixture in FIG. 20; and

FIG. 22 is a right side view of the orthodontic bracket in FIG. 21.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS First Embodiment

Referring to FIG. 1, reference numeral 2 denotes an orthodontic bracket placed on a side surface (or a front surface) of a tooth 1 subjected to orthodontic treatment. The tooth 1 in FIG. 1 is shown with its lower part as a gingival side (or a root side of the tooth).

The orthodontic bracket 2 comprises a bonding plate 3 a having a bonding surface matching a curve of the side surface of the tooth 1, a base 3 (see FIG. 3) having a bottom surface united with the bonding plate 3 a and an upper surface as a sliding surface 30 parallel to a vertical direction of the tooth 1, and taking an approximately rectangular shape in plan with a convex curve formed in accordance with a long axis (or the vertical direction) of the tooth 1, and a bracket body 4 set on the sliding surface 30 of the base 3 in such a way that the bracket body may slide along the long axis of the tooth 1.

As shown in FIGS. 1 to 7, the base 3 has, on the opposite upper sections of the sliding surface 30, confronting groove-like parallel rails 31, 31 so arranged as to approximately uniformly project from the sliding surface, the rails being adapted to let the opposite portions of the bracket body 4 therein slidably. Each rail 31 has, at its opposite ends, stoppers 31 a (see FIGS. 3 and 4) to prevent detachment of the bracket body 4. The sliding surface 30 has, at its widthwise center, a longitudinally-extending visible median line 30 a.

The bracket body 4 has, at its opposite sides of the upper surface, wings 40, 40 extending in parallel to the vertical direction of the tooth 1 and each having the opposite ends protruding in the above vertical direction. Each wing 40 has, at its longitudinal center, a wire slot 41 arranged approximately orthogonal to the corresponding wing 40 (or approximately orthogonal to the long axis of the tooth 1).

The orthodontic bracket according to the first embodiment is now described in detail.

While there is no limit on materials of the base 3 in particular, preferably available materials of the base 3 include ceramics such as aluminum oxide and aluminum nitride, epoxy, silicone or like hard resins, stainless steel, titanium alloy, cobalt-chromium alloy or other metals. The same is also substantially applied to materials of the bonding plate 3 a and/or the bracket body 4.

The median line 30 a on the sliding surface 30 of the base 3 is obtainable by coloring means of giving linear indication in loud color, or by mechanical means of giving notching, grooving or marking-off etc. to the sliding surface 30. Alternatively, a combination of the mechanical means with the coloring means is also applicable.

Each rail 31 of the base 3 has, at its opposite ends, hooks 31 b obtained by protruding upper parts of the above opposite ends by a prescribed distance in parallel to a longitudinal direction of the corresponding rail 31. In placement of the bracket body 4 on the sliding surface 30 of the base 3 using a ligature wire 5 without sliding, the ligature wire 5 is put on the upper- or lower-positional end hooks 31 b among the hooks 31 b.

To prevent damages to the inside of a lip, the tip end of each wing 40 extending in the vertical direction of the tooth from the opposite sides of the bracket body 4 takes a vertically-asymmetrical downwardly-curved shape as shown in FIG. 7 with the orthodontic bracket 2 placed on the tooth 1 according to the arrangement in FIG. 1.

Preferably, each wire slot 41 of the bracket body 4 takes an angular groove-like sectional shape with a gradient in one direction in section (see FIG. 7) to ensure that an arch wire 6 (see FIG. 1) held in position after being let in the corresponding wire slot 41 is hardly escaped from the corresponding wire slot 41. As shown in FIG. 6, the bracket body 4 has, at its substantially widthwise center, a longitudinally-through vertical slot 45.

The bracket body 4 has a bottom surface 43 having at least a pair of sliding bars 42, 42 (see FIGS. 6 and 7) spaced in parallel at a prescribed interval in such a way that each sliding bar lies across the bottom surface 43, and has a projecting portion extending in a circular-arc sectional shape from the bottom surface 43. The opposite ends of each sliding bar 42 serve to form guided parts supposed to be let slidably in the corresponding rail 31 of the base 3. The circular-arc projecting portion of each sliding bar 42 makes slidable contact with the sliding surface 30 of the base 3 as shown in FIG. 7 after placement of the bracket body 4 on the sliding surface 30 of the base 3.

A small projection of each sliding bar 42 from the bottom surface 43 of the bracket body 4 preferably requires that the bottom surface 43 of the bracket body 4 be in a concave-curved shape so as to mate the convex-curved shape of the base 3. This is because forming the bottom surface 43 of the bracket body 4 into the concave-curved shape allows the bottom surface 43 of the bracket body 4 to more successfully match the convex-curved shape of the sliding surface 30 of the base 3 in the case of the small projection of each sliding bar 42 from the bottom surface 43.

Preferably, the upper surface of the bracket body 4 has, at its widthwise center, a median line 44 of the same type as the median line 30 a on the sliding surface 30 such that the median lines 44 and 30 a are longitudinally in alignment with each other. The median line 44 functions, in cooperation with the median line 30 a on the sliding surface 30, as a mark useful in providing alignment of the axis of the base 3 including the bracket body 4 with the long axis of the tooth 1 when bonding the base 3 provided with the bracket body 4 on the sliding surface 30 to the side surface of the tooth 1, so that the alignment of the base with the corresponding tooth may be easily obtained.

Second Embodiment

FIGS. 8 to 10 are views showing the orthodontic bracket of a second embodiment according to the present invention including a modification of the bracket body.

In the second embodiment, there is provided a sliding plate 46 secured to the bottom of the bracket body 4, in which case, the opposite ends of the sliding plate 46 serve to form the guided parts supposed to be let in the corresponding rail 31 of the base 3. The sliding plate 46 has a bottom surface 46 a of a concave-curved shape (see FIG. 10) mating the convex-curved shape of the sliding surface 30 (see FIG. 3) of the base 3. The second embodiment has the sliding plate 46 having the bottom surface 46 a of the concave-curved shape as described the above, permitting the base 3 to be so placed on the side surface of the tooth 1 as to ensure that more successful matching of a posture of the bracket body 4 to the curve of the side surface of the tooth is obtainable, in cooperation with the base 3 having the sliding surface 30 of the convex-curved shape.

The orthodontic bracket of the second embodiment is the same as that of the first embodiment in configuration of the base 3, other configurations of the bracket body 4 and their operations and effects, so that their description is omitted.

A description is now given, with reference to FIGS. 11 and 12, on a case of intruding treatment of a tooth protruding from a tooth tip level (or by intruding it toward the root side of the tooth), among the teeth requiring occlusal adjustment between upper and lower premolars, using the orthodontic bracket of the above first embodiment.

For preparations, the bracket body 4 is first slidably set on the sliding surface 30 of the base 3 by letting the sliding bars 42, 42 (see FIG. 6) of the bracket body 4 in the respective rails 31 of the base 3.

The above preparations are followed by adhesive-bonding of each base 3 through its bonding plate to the protruding tooth la to be intruded and each of other teeth 1 involved in the intruding treatment, with each base 3 held such that the median line 30 a on the sliding surface 30 of each base 3 is in alignment with the long axis of the protruding tooth 1 a (or a higher-level tooth than a properly linear occlusal plane a) to be intruded and the long axis of each of the other teeth 1 involved in the intruding treatment, and also with each bracket body 4 held such that each axis (which is the same as the axis of the arch wire 6 described later) of the wire slots 41 of each bracket body 4 is arranged in parallel to the properly linear occlusal plane a (or a normally linear occlusal plane) obtained after intrusion of the protruding tooth 1 a.

Next, with the arch wire 6 held in position after being let in the wire slots 41 of each bracket body 4, attachment of a lower side of the ligature wire 5 serving as the fixture, for instance, to each hook 31 b located closer to the tooth tip, among the hooks of the rails 31 of the base 3, is performed by hooking, followed by fastening the bracket body 4 to the base 3 with the ligature wire 5 in cooperation with the arch wire 6 to prevent the above bracket body 4 from sliding along the sliding surface 30 of the corresponding base 3. At the same time, interconnection of the brackets 2 is performed.

Afterwards, insertion of the opposite ends of the above arch wire 6 into respective buccal tubes (not shown) united with more distal teeth is performed, followed by connection of the above arch wire to the respective buccal tubes to apply tension to the arch wire 6, and also to press each bracket 2 against each of the corresponding teeth 1 a and 1.

In this stage, each axis of the wire slots 41 (and the arch wire 6) in the bracket body 4 of the orthodontic bracket 2 set on the protruding tooth 1 a is arranged closer to the properly linear occlusal plane 1 than that of the other teeth 1 toward the tooth tip by a distance required for intrusion or somewhat exceeding the required distance.

With this arrangement, the protruding tooth 1 a requiring the intrusion gradually shifts toward the normally linear occlusal plane a (obtained after intrusion) such as to be given the intruding treatment.

When the intrusion of the protruding tooth 1 a to be intruded is advanced to a stage necessitating a change in setting of a bracket position with respect to the protruding tooth la to be intruded, repositioning of the bracket body 4 is performed by shifting the bracket body 4 along the sliding surface 30 of the base 3 by a required distance in the vertical direction of the protruding tooth 1 a to be intruded through the process of loosening or detaching the fixture such as the ligature wire 6, while loosening the arch wire 6. Then, with the repositioned bracket body 4 re-fixed to the sliding surface 80 of the base 3 by the fixture such as the ligature wire 6 without sliding, reinsertion of the opposite ends of the arch wire 6 into the respective buccal tubes is performed, followed by reconnection of the arch wire to the respective buccal tubes to reapply tension to the arch wire 6.

Thus, there is no need to reset the bracket body 4 and/or the arch wire 6 every time the intrusion of the protruding tooth la etc. to be intruded is advanced to the stage necessitating the change in setting of the bracket position with respect to the protruding tooth 1 a etc. to be intruded. Accordingly, the orthodontic bracket of the present invention enables the orthodontic treatment to be performed in a shorter period of time, and also may contribute to relieve the patient from one's burden by far.

Further, the orthodontic bracket of the present invention has the base 3 of the convex-curved shape in accordance with the vertical direction of the tooth, and the bracket body 4 having the concave-curved bottom surface 43 mating the convex-curved base 3, permitting more successful matching of the convex-curved base 3 to the tooth side surface to be obtained, and also permitting the installed posture of the bracket body 4 set on the sliding surface of the convex-curved base 3 to match the tooth side surface more successfully.

When alignment of the tooth tip of the protruding tooth 1 a with the normally linear occlusal plane a, and hence, parallel arrangement of the axis of the arch wire 6 with the normally linear occlusal plane a is obtained as a result of further advance of the intrusion of the protruding tooth 1 a, the intrusion of the protruding tooth 1 a is completed.

For extruding treatment of a retreating tooth 1 b having the tip lower than the normally linear occlusal plane a or standing back toward the root side of the tooth, among the teeth 1 requiring the orthodontic treatment (or extruding it toward the tooth tip side), attachment of the orthodontic bracket 2 to the retreating tooth 1 b to be extruded is performed according to the arrangement shown in FIG. 13. Specifically, the ligature wire 5 is put on each hook 31 b located closer to the root of the tooth among the hooks in the rails 31 of the base 3. Further, each axis of the arch wire 6 and the wire slots 41 of the bracket 2 set on the retreating tooth 1 b is arranged more distant from the properly linear occlusal plane a than the other teeth 1 toward the root side of the tooth by a distance required for exclusion or somewhat exceeding the required distance.

A completed state of extrusion of the retreating tooth 1 b is as shown in FIG. 14. Details of other procedures taken to attach each orthodontic bracket to the tooth and/or other operations and effects of each orthodontic bracket are the same as those previously described with reference to FIGS. 11 and 12.

For the orthodontic treatment other than exclusion and intrusion of the tooth, that is, distal movements (or movements from an incisor side toward molars) or mesial movements (or movements from a molar side toward incisors) of the tooth to be orthodontically treated, attachment of the orthodontic bracket 2 to each tooth 1 subjected to distal or mesial movements is performed according to the arrangement shown in FIG. 1. Procedures taken to attach each orthodontic bracket in this case are substantially the same as the previously described procedures.

The same procedures as the previously described procedures may be also applied to the orthodontic treatment using the orthodontic bracket 2 according to the second embodiment.

The bracket is usually bonded to an accurate bracket position with a jig or a gauge. A fixation apparatus for fixing the bracket body to an arbitrary place of the base allows usual use of a slide-type bracket as being bonded to an accurate bracket position with the jig or the gauge like the conventional bracket. The fixation apparatus is of a detachable type. Thus, a slide function may be fulfilled by detaching the fixation apparatus at needed, or use as the bracket as usual may be made by resetting the fixation apparatus. The following is a description on some proposed fixation apparatuses applicable to this type of fixation apparatus (or a fixture 5 a).

Third Embodiment

FIGS. 15 and 16 show a third embodiment of the orthodontic bracket involving use of a fixture substituted for the ligature wire. It is to be noted that configurations and/or arrangements of the base 3 and the bracket body 4 in the third embodiment except a fixture-related portion are the same as those in the second embodiment, and hence, their description is omitted. The same is also applied to fourth and fifth embodiments described later.

The fixture 5 a is in the form of a member taking an approximately U-like shape in plan and composed of a basal part 50 supposed to be arranged in parallel to an outside surface of one rail 31 with the fixture attached to the base 3, and a pair of linear legs 51, 51 extending from and approximately orthogonal to the opposite ends of the basal part 60 in one direction, the linear legs being adaptable to hold the bracket body 4 set on the sliding surface 30 of the base 3 from the upper and lower sides of the bracket body. On the other hand, the rails 31, 31 of the base 3 have, in four locations, holes 31 c, 31 c adaptable to provide through-passage of the respective linear legs 51 of the fixture 5 a from one side of the base 3 to the other side at approximately right angles to the corresponding rails 31.

After passage of the linear legs 51, 51 of the fixture 5 a through the corresponding holes 31 c from one side of the base 3 (see FIG. 15), thrust or insertion of a lower part of the bracket body 4 into a space enclosed by the rails 31 and the linear legs 51 allows the bracket body 4 to be attached to the sliding surface 30 of the base 3 without sliding.

The third embodiment preferably makes arrangements for the arch wire 6 to be let in the wire slots 41 of the bracket body 4 after placement of the bracket body 4 to the base 3 in the above manner (the same is also applied to the fourth and fifth embodiments).

It is to be noted that each linear leg 51 preferably has, at its tip end surface, a depression 51 a. With this arrangement, use of a dental equipment or an explorer (not shown) having a tip end in the form of a hook-like pin, for instance, for drawing out each linear leg 51 through each corresponding hole 31 c allows easy detachment of the fixture 5 a by taking advantage of a clearance left between one rail 31 and the base 50 under conditions in FIG. 15 in such a way as to push out the linear leg 51 by a small distance in its pushing-out direction with the pin tip end pressed into contact with the depression 51 a.

Fourth Embodiment

FIGS. 17 to 19 show the fourth embodiment of the orthodontic bracket involving use of a fixture of a different type substituted for the ligature wire.

The fixture 5 a is composed of at least a pair of spacer members 62, 62 each having the opposite ends supposed to be let in each rail 31 of the base 3 with spacer member sliding restricted by the stoppers 31 a of the corresponding rail 30, the spacer members being adaptable to hold the bracket body 4 set on the sliding surface 30 of the base 3 from the upper and lower sides of the bracket body with the spacer members placed in the respective rails.

Each spacer member 52 takes a plate-like form, and one end of each spacer member 52 or one end supposed to be let in one rail 31 is in the form of a wedge having a thickness gradually decreasing as being closer to its tip end as shown in FIG. 19. Setting of the spacer members 52 on the base 3 according to the arrangement in FIGS. 17 and 18 is performed in the manner of inserting one wedge-like end of each spacer member 52 into one rail 31 from the upper side of the base 3 into contact of the inserted spacer member 52 with the sliding surface 30 as shown in FIG. 19, followed by pressing in the other end of the inserted spacer member by a small distance toward the other rail 31.

With the fixture 5 a set on the sliding surface 30 of the base 3 as shown in FIG. 17, thrust or insertion of the lower side of the bracket body 4 into the space enclosed by the rails 31 and the spacer members 52 allows the bracket body 4 to be attached to the sliding surface 30 of the base 3 without sliding.

It is to be noted that at least one side of each spacer member 52 preferably has, at its back surface, a groove-like notch 52 a (see FIG. 19). With this arrangement, use of the dental equipment or the explorer (not shown) having the tip end in the form of the hook-like pin, for instance, for detaching the spacer members 62 from the base 3 allows easy detachment of each spacer member by hooking the pin of the explorer on the notch 52 a.

Fifth Embodiment

FIGS. 20 to 22 show the fifth embodiment of the orthodontic bracket involving use of a fixture of a further different type substituted for the ligature wire.

The fixture 5 a is formed of an elastic metal member having a basal part 53 supposed to be arranged in parallel to one rail 31 of the base 3 with the bracket body 4 set on the sliding surface 30 of the base 3.

The basal part 53 has, at its opposite ends, a pair of first arms 54, 54 as an integral unit extending from and approximately orthogonal to one side of the basal part 53 and supposed to be let in the rails in such a way as to pass under the hook 31 b of one rail 31 and the corresponding hook 31 b of the other rail 31 in this order. Each of the first arms has, at its tip end, a hook 54 a supposed to be hooked on the outer surface of the corresponding end of the other rail 31.

The basal part 53 has, at its portions close to the center, a pair of second arms 55, 55 as an integral unit extending from and approximately orthogonal to the above-mentioned one side of the basal part so as to cross the upper surface of each rail 31 of the base 3, the second arms being adaptable to hold the bracket body 4 set on the sliding surface 30 of the base 3 from the upper and lower sides of the bracket body.

Further, the hook 54 a in each first arm has, at its tip end, a concave-shaped notch 54 b.

Attachment of the wholly wedge-shaped fixture 5 a to the base 3 according to the arrangement in FIG. 21 allows each rail 31 of the base 3 to be held from both the upper and lower surfaces by elastic force of the pairs of first and second arms 54 and 55. Then, thrust or insertion of the lower side of the bracket body 4 into the space enclosed by the second arms 55 and the rails 31 allows the bracket body 4 to be attached on the sliding surface 30 of the base 3 without eliding.

The hook 54 a in each first arm 54 has, at its tip end, the concave-shaped notch 54 b, so that use of the dental equipment or the explorer (not shown) having the tip end in the form of the hook-like pin, for instance, for detaching the fixture 5 a from the base 3 allows easy detachment of the fixture by hooking the pin of the explorer on the concave-shaped notch 54 b.

The orthodontic bracket of the present invention is also applicable to orthodontic treatments according to an edgewise or tip edge technique. 

1. An orthodontic bracket placed on a side surface of a tooth for correcting irregularities of teeth, comprising; a bonding plate having a bonding surface matching a curve of said tooth; a base having a bottom surface united with said bonding plate and an upper surface as a sliding surface parallel to a long axis of the tooth and taking an approximately rectangular shape in plan with a convex curve formed in accordance with the long axis of said tooth; and a bracket body set on said sliding surface of said base in such a way that the bracket body may slide along the long axis of said tooth; wherein said base has, on the opposite upper sections of said sliding surface, confronting groove-like parallel rails adapted to let the opposite portions of said bracket body therein slidably, each rail having, at its opposite ends, stoppers to prevent detachment of said bracket body, said sliding surface having, at its widthwise center, a longitudinally-extending visible median line; and said bracket body has, on its upper surface, wire slots arranged approximately orthogonal to the long axis of said tooth.
 2. The orthodontic bracket according to claim 1, wherein each rail of said base has, at its opposite ends, hooks obtained by protruding the upper parts of said opposite ends in parallel to a longitudinal direction of the corresponding rail.
 3. The orthodontic bracket according to claim 1, wherein said bracket body has, on its bottom, at least a pair of sliding bars arranged across said bottom and each having a projecting portion extending in a circular arc sectional shape from the surface of said bottom, and the opposite ends of each sliding bar serve to form guided parts supposed to be let in the corresponding rail of said base.
 4. The orthodontic bracket according to claim 3, wherein the bottom of said bracket body is in a concave-curved shape mating the convex-curved shape of said base.
 5. The orthodontic bracket according to claim 1, wherein said bracket body has, on its bottom, a sliding plate, the opposite ends of said sliding plate serve to form guided parts supposed to be let in the corresponding rail of said base, and the bottom of said sliding plate is in a concave-curved shape mating the convex-curved shape of said base.
 6. The orthodontic bracket according to claim 1, wherein it further comprises a fixture for attaching said bracket body to the sliding surface of said base without sliding along at least said sliding surface.
 7. The orthodontic bracket according to claim 6, wherein said fixture is in the form of a member taking an approximately U-like shape in plan and composed of a pair of linear legs adaptable to hold said bracket body set on the sliding surface of said base in accordance with the vertical direction of said tooth, and each rail of said base has holes adaptable to provide through-passage of each linear leg of said fixture from one side of said base at approximately right angles to said each rail.
 8. The orthodontic bracket according to claim 7, wherein each linear leg of said fixture has, at its tip end surface, a depression.
 9. The orthodontic bracket according to claim 6, wherein said fixture is composed of at least a pair of spacer members each having the opposite ends supposed to be let in the corresponding rail with spacer member sliding restricted by said stoppers of each corresponding rail, said spacer members being adaptable to hold said bracket body set on the sliding surface of said base in accordance with the vertical direction of said tooth, with said spacer members placed in the rails.
 10. The orthodontic bracket according to claim 9, wherein at least one side of each spacer member specified as said fixture has, at its back surface, a notch.
 11. The orthodontic bracket according to claim 2, wherein it further comprises a fixture for attaching said bracket body to the sliding surface of said base without sliding along at least said sliding surface, said fixture being formed of an elastic metal member having a basal part supposed to be arranged in parallel to one rail of said base with said bracket body set on the sliding surface of said base, a pair of first arms formed as an integral unit extending from and approximately orthogonal to one side of said basal part and supposed to be let in the rails in such a way as to pass under a hook in said one rail and a hook in the other rail in this order, and a pair of second arms formed as an integral unit extending from and approximately orthogonal to said one side of said basal part so as to cross the upper surface of each rail of said base, said second arms being adaptable to hold said bracket body set on the sliding surface of said base in accordance with the vertical direction of said tooth, each first arm having, at its tip end, a hook supposed to be hooked on an outer surface of a corresponding end of said other rail.
 12. The orthodontic bracket according to claim 11, wherein each second arm has a hook having, at its tip end, a concave-shaped notch. 